The present invention is directed to an optical coupling element having a convex, refractive microlens being mounted in a through-hole shaped like a truncated pyramid or cone of a flat carrier lamina having flat surfaces, with one of the flat surfaces being securable to a body that carries a light-emitting and/or light-receiving optical component which light passes through the microlens. The invention is also directed to a method of manufacturing the optical coupling element having the microlens.
An optical coupling element of the above-mentioned type is disclosed in EP 0 280 305 Al. In this known element, the microlens is composed of a sapphire ball that is secured with a glass solder in a hole shaped like a truncated pyramid in a carrier lamina. For fastening the carrier lamina to a body, the carrier lamina is provided with metallizations for soldering.
Due to the rather high spherical aberrations, spherical lenses are not well-suited for coupling optics that should be extremely low-loss.
European Patent Application No. 88 118 337.0 and U.S. Pat. No. 4,830,454, whose disclosure is incorporated herein by reference thereto, each disclose a plano-convex lens in the form of a ball of silicon or germanium that is flattened on one surface. This spherical planar convex lens can be used as a coupling element which achieves a high coupling efficiency.